Method for obtaining contact lenses with dynamically controlled sagitta and clearance
AssigneeBausch & Lomb Incorporated
InventorCharles H. Creighton
Life of this patent
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Abstract
The disclosure generally describes methods, systems and products relating to the development and manufacture of scleral contact lenses. A number of dimensions for the scleral lens is generated based on control points and attendant curvature parameters. Any change to one or more of the curve parameters imparts an improved anterior and posterior surface of the scleral lens and associated thickness, while undesired modifications to control points and other curve parameters remain static inasmuch as the sagittal depth component is an input parameter of the present disclosure.
Claims20
A method of designing and manufacturing a scleral contact lens for a user, comprising:
- (a) defining segment parameters for a surface of a scleral contact lens comprising a base curve segment positioned in a central portion of the lens, a dynamic curve segment peripherally surrounding the base curve segment, a limbal clearance curve segment peripherally surrounding the dynamic curve segment, and a peripheral curve segment peripherally surrounding the limbal clearance curve segment, wherein the base curve segment is defined by segment parameter components comprising a base curve sagittal component SA, a base curve radius component RA, and a base curve chord diameter component DA, the dynamic curve segment is defined by segment parameter components comprising a dynamic curve sagittal component SB, a dynamic curve radius component RB, and a dynamic curve chord diameter component DB, the limbal clearance curve segment is defined by segment parameter components comprising a limbal clearance curve sagittal component SC, a limbal clearance curve radius component RC, and a limbal clearance curve chord diameter component DC, the peripheral curve segment is defined by segment parameter components comprising a peripheral curve sagittal component SD, a peripheral curve radius component RD, and a peripheral curve chord diameter component DD;
- (b) specifying each of the segment parameter components RA, RC, RD, DA, DB, DC, DD and a total sagittal clearance STOTAL comprising the sum of SA, SB, SC and SD for the scleral contact lens;
- (c) calculating the dynamic curve radius RB and each of the sagittal components SA, SB, SC and SD based on the specified parameter components RA, RC, RD, DA, DB, DC, DD and STOTAL according to the following algorithms;
- Notation
- Parameter
- Formula/Calculation
- (SA)
- Base Curve
- = RA − sqrt(RA{circumflex over ( )}2 − (DA/2){circumflex over ( )}2)
- Sagittal
- Component
- (SC)
- Limbal
- = RC − sqrt(RC{circumflex over ( )}2 − (DC/2){circumflex over ( )}2) −
- Clearance Curve
- RC − sqrt(RC{circumflex over ( )}2 − (DB/2){circumflex over ( )}2)
- Sagittal
- Component
- (SD)
- Peripheral Curve
- = RD − sqrt(RD{circumflex over ( )}2 − DD/2){circumflex over ( )}2) −
- Sagittal
- RD − sqrt(RC{circumflex over ( )}2 − (DC/2){circumflex over ( )}2)
- Component
- (SB)
- Dynamic Curve
- = Stotal − SD − SC − SA
- Sagittal
- Component
- (RB)
- Dynamic Curve
- = SQRT(((DA/2){circumflex over ( )}2) + ((((((DB/2){circumflex over ( )}2) −
- Radius
- ((DA/2){circumflex over ( )}2)) + (SB{circumflex over ( )}2))/(2*SB)){circumflex over ( )}2)))
- and
- (d) forming a scleral contact lens to have a surface corresponding to the specified parameter components RA, RC, RD, DA, DB, DC, DD and STOTAL and calculated parameters components RB, SA, SB, SC and SD.
Dependencies are inferred from the claim text.